This invention relates to monolithic electronic circuits and more particularly to a distributed mixer.
In the past mixer techniques have included single or dual gate field effect transistors (FETs) used in numerous types of configurations ranging from single ended to dual balanced rings. Nevertheless, none of the techniques have achieved broadband performance, and this includes circuits employing external baluns and multiple devices. The use of baluns provides the best performance of all, but they cannot be implemented using monolithic circuit fabrication methods.
There are also other circuit constraints limiting the performance of single or dual gate FET mixers. With single gate devices, it is difficult, even with baluns, to inject the required local oscillator (LO) energy needed for operation. Broadband performance is also difficult to achieve owing to the wide impedance variations encountered at the gate and drain of any FET. The LO injection problem is eliminated with the dual gate FET, but impedance matching and stability problems still exist.